OAKLAND — Forty-eight hours earlier, an upbeat group of Yankees, fresh off a three-game sweep of the Mariners, strutted into O.Co Coliseum Friday to deliver a resounding drubbing of the Athletics, the American League’s leading outfit.

The triumph was their most impressive of the season. The clubhouse mood was lively. Laughs were plentiful. The team was confident. They owned a four-game winning streak. The offense finally seemed on its way out of a perpetual slump to complement the pitching staff's efforts.

By mid-Sunday afternoon, those positive vibes had emphatically ceased, a product of the 10-5 trouncing the Athletics handed the Yankees to claim the three-game weekend series and complete the Yankees' nine-game road trip. Suddenly, the visitors departed the Bay Area for New York a humbled bunch with a two-game losing steak and a six-game gauntlet — against division rivals Blue Jays and Orioles — awaiting at Yankee Stadium.

“When we were 5-2 and had a chance to have a really good road trip it kind of stings a little bit,” Girardi said. “But you got to keep big picture.”

The vaunted Athletics offense surfaced on Father’s Day, thrashing an overmatched Vidal Nuno to establish an early insurmountable advantage. Four batters in, Nuno (1-2, 5.90 ERA) surrendered a mammoth three-run home to the bearded Derek Norris. Coco Crisp duplicated Norris’s effort in the second inning, launching another three-run shot over the left-field wall.

“They hit the ball out of the ballpark and you have to control that,” Girardi said. “Today we weren’t able to do that and they flexed their muscle today and beat us bad.”

Nuno escaped the frame and retired the Athletics (42-27) in order in the third inning. But he would not record another out. The left-hander departed from the contest in the fourth inning with no outs and runners on first and second.

His replacement Jose Ramirez did not fare much better. The hard-throwing right-hander walked Crisp to load the bases and hit Craig Gentry in the head to force home a run. He then yielded a single to Yoenis Céspedes that plated another run. Both runs were charged to Nuno.

Ramirez yielded two more runs and when the dust settled, Nuno had recorded his worst outing of the season. He allowed eight runs on eight hits over the three-plus innings and watched his earned-run average hike from 4.97 to 5.90. It was the shortest start of the season for the rotation fill-in, who was assigned to replace the injured Ivan Nova at the end of April.

“It all happened so quick,” Nuno lamented.

The Yankees could not counter. After tallying 13 runs between Thursday and Friday to break a head-scratching streak of 12 games in which they scored fewer than four runs per game, the Yankees (36-32) mustered three over the road trip’s final two games.

Athletics starter Jesse Chavez continued his stunning breakout campaign, silencing the Yankees over six innings. Chavez (6-4, 2.93 ERA) yielded one run on five hits and struck out four batters. He did not issue a walk.

The only damage the Yankees could inflict on Chavez occurred in the sixth inning, when they were already down 10-0. Derek Jeter, playing his final regular season game on the West Coast, blasted a double to the warning track in left-center field. Next, Mark Teixeira, in the lineup after being scratched with tightness in his left rib cage Saturday, doubled Jeter home.

Carlos Beltrán added a leadoff home run off Ryan Cook — his first since April 22 — in the Yankees’ two-run seventh inning, but followed the swat with a perplexing gaffe the next frame.

With one out, Beltrán hit a groundball to shortstop Jed Lowrie, who tossed the ball to second base to retire Brian McCann. Beltrán reached first base without a throw, but, believing the force play was the inning’s third out, he jogged toward the dugout. He realized his mistake too late and was tagged out.

“It’s an embarrassing play,” Girardi said.

Brett Gardner clubbed a two-run home run in the ninth, but the Yankees’ fate had already been determined; their trip, though successful, already been determined. They are off today, followed by a three-game set opposite the first-place Blue Jays to begin a 15-game stretch versus American League East foes.

“We have tomorrow off. I think it’s needed — for everyone,” Jeter said. “It’s been a long trip for us.”